/*
 * Copyright 2002-2020 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.web.cors.reactive;

import java.util.LinkedHashMap;
import java.util.Map;

import org.springframework.http.server.PathContainer;
import org.springframework.lang.Nullable;
import org.springframework.web.cors.CorsConfiguration;
import org.springframework.web.server.ServerWebExchange;
import org.springframework.web.util.pattern.PathPattern;
import org.springframework.web.util.pattern.PathPatternParser;

/**
 * {@code CorsConfigurationSource} that uses URL patterns to select the
 * {@code CorsConfiguration} for a request.
 *
 * @author Sebastien Deleuze
 * @author Brian Clozel
 * @see PathPattern
 * @since 5.0
 */
public class UrlBasedCorsConfigurationSource implements CorsConfigurationSource {

    private final PathPatternParser patternParser;

    private final Map<PathPattern, CorsConfiguration> corsConfigurations = new LinkedHashMap<>();


    /**
     * Construct a new {@code UrlBasedCorsConfigurationSource} instance with default
     * {@code PathPatternParser}.
     *
     * @since 5.0.6
     */
    public UrlBasedCorsConfigurationSource() {
        this(PathPatternParser.defaultInstance);
    }

    /**
     * Construct a new {@code UrlBasedCorsConfigurationSource} instance from the supplied
     * {@code PathPatternParser}.
     */
    public UrlBasedCorsConfigurationSource(PathPatternParser patternParser) {
        this.patternParser = patternParser;
    }


    /**
     * Set CORS configuration based on URL patterns.
     */
    public void setCorsConfigurations(@Nullable Map<String, CorsConfiguration> configMap) {
        this.corsConfigurations.clear();
        if (configMap != null) {
            configMap.forEach(this::registerCorsConfiguration);
        }
    }

    /**
     * Register a {@link CorsConfiguration} for the specified path pattern.
     */
    public void registerCorsConfiguration(String path, CorsConfiguration config) {
        this.corsConfigurations.put(this.patternParser.parse(path), config);
    }

    @Override
    @Nullable
    public CorsConfiguration getCorsConfiguration(ServerWebExchange exchange) {
        PathContainer path = exchange.getRequest().getPath().pathWithinApplication();
        for (Map.Entry<PathPattern, CorsConfiguration> entry : this.corsConfigurations.entrySet()) {
            if (entry.getKey().matches(path)) {
                return entry.getValue();
            }
        }
        return null;
    }

}
